The Surface-Imprinted Thermosensitive Core-Shell Nanosphere

Abstract

The molecular imprinting techniques have been extensively studied for molecular recognition and their potential applications to separation and catalysis. The traditional imprinting method uses the crosslinking polymerization in the presence of a substrate molecule followed by grinding the bulk system to microparticles with an irregular shape. In addition, the imprinting is restricted to a hydrophobic substrate because the polymerization reaction is usually done in the organic solvent using hydrophobic monomers. In this case, the irregular shape and microparticle size might be a concern for microelectromechanical system (MEMS) application as a biosensor. In this study, we investigated a well-defined nanosphere with a core-shell structure for molecular imprinting. The hydrophilic substrates including D-glucose (D-Glu) or L-phenylalanine (L-Phe) were imprinted on the surface (shell) of nanosphere and their binding behavior were investigated. Their enantiomer (L-Glu or D-Phe) binding behavior to the surface of imprinted core-shell nanosphere as well as to the nonimprinted core-shell nanosphere was also compared as a reference. The change in the tertiary structure of a protein, that is, denaturation, causes the change in the binding ability of a substrate. The shell of the nanosphere was designed to undergo hydrophilic to hydrophobic transition by small change in temperature to mimic the conformational change in the binding site. This finding indicates that the surface imprinted core-shell nanosphere can be used for bioassay with specific substrate. The target molecules related to a disease can be imprinted in the shell of the core-shell nanosphere. Then, the substrate will bind to the imprinted site when the substrate concentration is high enough. In other potential applications are the treatments of a contaminated person with toxic molecules. The contaminated toxic molecules in a body can be extracted with a core-shell nanosphere when the surface imprinted nanosphere is inoculated.